Sorption cooling process and system

Abstract

A process and a system are disclosed for sorption heating and cooling which comprise at least 2 sorption zones. Each sorption zone comprises a heat transfer zone and an adsorption zone containing a sorbent such that the heat transfer zone is in intimate thermal contact with the adsorption zone to permit an essentially uniform temperature lengthwise through the sorption zone and thereby employ essentially all of the sorbent in the process at all times. The process comprises passing heat transfer streams such as a hot stream, a cold stream, and a recirculation stream through the heat transfer zone and routing a refrigerant through the adsorption zone of each sorption zone to affect a desorption stroke, an intermediate stroke and an adsorption stroke in the adsorption zone. Rotary and multi-port valves are employed to circulate the refrigerant and the heat transfer streams. The resulting sorption cooling process achieves a significantly higher coefficient of performance than the prior art.

We claim: 
     
       1. A process for sorption heating and cooling comprising the following steps: a. supplying a first hot stream to a first sorption zone of at least 2 sorption zones, each sorption zone comprising a heat transfer zone and a separate adsorption zone, said adsorption zone containing a sorbent, said heat transfer zone being in intimate indirect thermal contact with said adsorption zone to permit an essentially uniform temperature throughout said sorption zone to desorb a refrigerant vapor from the adsorption zone of said first sorption zone at an upper pressure and provide a hot exit stream from the heat transfer zone of said first sorption zone;   b. passing the refrigerant vapor stream to a cooler and condenser zone to provide a condensate stream, reducing the pressure of the condensate stream to a lower pressure to provide a reduced pressure condensate, and passing the reduced pressure condensate to an evaporator zone to provide a revaporized refrigerant stream;   c. passing a cold stream to the heat transfer zone of a second sorption zone and recovering a cold exit stream, and simultaneously conducting the revaporized refrigerant stream to the adsorption zone of said second sorption zone to adsorb the revaporized refrigerant;   d. simultaneously terminating the passing of refrigerant vapor from said first sorption zone, terminating the passing of said hot stream to the heat transfer zone of said first sorption zone, terminating the passing of the cold stream to the second sorption zone, and passing a recirculation stream between the heat transfer zone of the first sorption zone and the heat transfer zone of the second sorption zone; and   e. repeating the above steps (a) through (d) to provide a sorption cooling or heating cycle wherein said first sorption zone and second sorption zone alternately undergo a desorption stroke in step (a), an adsorption stroke in step (c), and an intermediate stroke in step (d) between alternate adsorption and desorption strokes.   
     
     
       2. The process of claim 1 wherein said process comprises at least 6 sorption zones wherein at least two sorption zones simultaneously undergo the adsorption stroke, at least two sorption zones simultaneously undergo the desorption stroke, and at least two sorption zones are simultaneously undergoing the intermediate stroke to provide a continuous sorption heating and cooling process. 
     
     
       3. The process of claim 1 further comprising returning the hot exit stream to a hot source and returning the cold exit stream to a cold source. 
     
     
       4. The process of claim 3 further comprising passing the hot exit stream through the heat transfer zone of at least two sorption zones simultaneously undergoing the desorption stroke prior to returning said hot exit stream to said hot source. 
     
     
       5. The process of claim 1 further comprising returning the hot exit stream to a hot source to provide said hot stream. 
     
     
       6. The process of claim 1 further comprising returning the cold exit stream to a cold source to provide said cold stream and cooling the hot exit stream to provide said cold stream. 
     
     
       7. A process for sorption heating and cooling comprising the following steps: a. supplying a first hot stream through a first rotary valve section to a first sorption zone of at least 2 sorption zones, each sorption zone comprising a heat transfer zone and a separate adsorption zone, said adsorption zone containing a sorbent, said heat transfer zone being in intimate indirect thermal contact with said adsorption zone to permit an essentially uniform temperature throughout said sorption zones to desorb a refrigerant vapor from the adsorption zone of said first sorption zone at an upper pressure and provide a hot exit stream from the heat transfer zone of said first sorption zone;   b. passing the refrigerant vapor stream through a second rotary valve section to a cooler and condenser zone to provide a condensate stream, reducing the pressure of the condensate stream to a lower pressure to provide a reduced pressure condensate, and passing the reduced pressure condensate to an evaporator zone to provide a revaporized refrigerant stream;   c. passing a cold stream through said first rotary valve section to the heat transfer zone of a second sorption zone and recovering a cold exit stream, and simultaneously conducting the revaporized refrigerant stream through a third valve zone to the adsorption zone of said second sorption zone to adsorb the revaporized refrigerant;   d. advancing said second rotary valve section to terminate the passing of refrigerant vapor from said first sorption zone through said second rotary valve section and advancing the first rotary valve section to simultaneously terminate the passing of said hot stream to the heat transfer zone of said first sorption zone and terminate the passing of the cold stream to the second sorption zone, and simultaneously through said first rotary valve section passing a recirculation stream between the heat transfer zone of the first sorption zone and the heat transfer zone of the second sorption zone; and   e. indexing the position of the first and second rotary valve sections in unison to repeat the above steps (a) through (d) to provide a sorption cooling or heating cycle wherein said first sorption zone and the second sorption zone alternately undergo a desorption stroke in step (a), an adsorption stroke in step (c), and an intermediate stroke in step (d) between alternate adsorption and desorption strokes.   
     
     
       8. The process of claim 7 wherein the third valve zone comprises a check valve or a third rotary valve section. 
     
     
       9. The process of claim 7 wherein said process comprises at least 6 sorption zones wherein at least two sorption zones are undergoing the adsorption stroke, at least two sorption zones are undergoing the desorption stroke, and at least two sorption zones are undergoing the intermediate stroke and wherein the hot exit stream is passed through the first rotary valve section to another sorption zone undergoing the desorption stroke, and the cold exit stream is passed through the second rotary valve section to another zone undergoing the adsorption stroke to provide a continuous sorption cooling and heating process. 
     
     
       10. The process of claim 7 wherein the refrigerant vapor is selected from the group consisting of water, alcohols, ammonia, light hydrocarbons, and mixtures thereof. 
     
     
       11. The process of claim 7 wherein the sorbent comprises a solid sorbent selected from the group consisting of silica gel, activated carbon, clays, metallic salts, zeolite molecular sieves, and mixtures thereof. 
     
     
       12. The process of claim 7 wherein the sorbent is selected from the group consisting of zeolite A, zeolite X, zeolite Y, and mixtures thereof. 
     
     
       13. The process of claim 7 wherein the refrigerant vapor comprises water and the sorbent comprises zeolite Y. 
     
     
       14. The process of claim 7 wherein the sorbent is selected from the group consisting of zeolites Y-54, Y-74, Y-84, Y-85, low cerium rare earth exchanged Y-84, low cerium rare earth exchanged LZ-210, and mixtures thereof. 
     
     
       15. The process of claim 7 wherein said refrigerant vapor is water and the upper pressure ranges between about 2 kPa (15 torr) and about 20 kPa (150 torr), and the lower pressure ranges between about 0.6 kPa (46 torr) and about 2 kPa (15 torr). 
     
     
       16. A process for sorption heating and cooling comprising the following steps: a. supplying a first hot stream through a first rotary valve section and a first conduit to a first sorption zone of at least 2 sorption zones, each sorption zone comprising a heat transfer zone and a separate adsorption zone, said adsorption zone containing a sorbent coated surface, said heat transfer zone being in intimate indirect thermal contact with said adsorption zone to permit an essentially uniform temperature throughout said sorption zones to desorb a refrigerant vapor from the adsorption zone of said first sorption zone at an upper pressure and provide a hot exit stream from the heat transfer zone of said first sorption zone;   b. passing the refrigerant vapor stream through a second conduit and a second rotary valve section to a cooler and condenser zone to provide a condensate stream, reducing the pressure of the condensate stream to a lower pressure to provide a reduced pressure condensate, and passing the reduced pressure condensate to an evaporator zone to provide a revaporized refrigerant stream;   c. passing a cold stream through said first rotary valve section and a third conduit to the heat transfer zone of a second sorption zone and recovering a cold exit stream, and simultaneously conducting the revaporized refrigerant stream through a fourth conduit and a third valve zone to the adsorption zone of said second sorption zone to adsorb the revaporized refrigerant;   d. advancing said second rotary valve section to terminate the passing of refrigerant vapor from said first sorption zone through said second conduit and said second rotary valve section and advancing the first rotary valve section to simultaneously terminate the passing of said hot stream through said first conduit to the heat transfer zone of said first sorption zone, to simultaneously terminate the passing of the cold stream through said third conduit to the second sorption zone, and to simultaneously circulate a recirculation stream through a fifth conduit, said first rotary valve section, and the heat transfer zone of the first sorption zone and returning said recirculation stream through a sixth conduit and said first rotary valve section to the heat transfer zone of the second sorption zone; and   e. indexing the position of the first and second rotary valve sections in unison to repeat the above steps (a) through (d) to simultaneously alternate the conduits carrying the hot and cold streams, the refrigerant vapor and revaporized refrigerant stream, and the recirculation stream wherein the first and second sorption zones alternately undergo a desorption stroke, an adsorption stroke, and an intermediate stroke between alternate adsorption and desorption strokes to provide a continuous process.   
     
     
       17. The process of claim 16 further comprising exchanging heat between the evaporator zone and either a plant process stream or a conditioned space to provide heating or cooling of the process stream or the conditioned space. 
     
     
       18. The process of claim 16 further comprising heating the evaporator with a plant process stream selected from the group consisting of steam, water, hydrocarbons, fluid chemicals, air, gases and mixtures thereof. 
     
     
       19. A sorption cooling system comprising a condenser; an evaporator; at least two sorption zones each sorption zone containing a solid adsorbent selective for the adsorption of at least a portion of a refrigerant fluid, containing a heat transfer section in close indirect thermal communication with said solid adsorbent, and having a heat transfer fluid passage for a heat transfer fluid; a hot source; a cold source; a single rotary distribution valve for simultaneously and separately conveying the heat transfer fluid at a desorption temperature from the hot source to the heat transfer section of a first sorption zone in a desorption stroke to provide a desorbed refrigerant vapor and returning said hot heat transfer fluid to said hot source, for simultaneously and separately conveying a cold heat transfer fluid at an adsorption temperature from the cold source to a second sorption zone in an adsorption stroke and returning said cold heat transfer fluid to said cold source, for simultaneously terminating the flow of refrigerant vapor to or from said first and second sorption zones while separately circulating a recirculation fluid in an intermediate stroke between a sorption zone having completed the desorption stroke with the sorption zone having completed the adsorption stroke, for simultaneously and separately conveying at least a portion of said desorbed refrigerant vapor to the condenser to provide a condensate stream, for simultaneously and separately conveying said condensate stream to said evaporator under a reduced pressure to provide a vaporized refrigerant stream and for simultaneously and separately conveying said vaporized refrigerant stream from said evaporator to said second sorption zone in the adsorption mode; a conduit for conveying said condensate stream from said condenser to said evaporator; and a valve indexing driver to advance the single rotary distribution valve to simultaneously step the first sorption zone to the adsorption mode, simultaneously step the other sorption zone to the desorption mode, and simultaneously cycle and alternately convey the heat exchange fluid to and from the hot source and the cold source to provide a continuous sorption cooling system. 
     
     
       20. The sorption cooling system of claim 19 wherein said hot source comprises a hot temperature equal to or greater than said desorption temperature. 
     
     
       21. The sorption cooling system of claim 19 wherein said cold source comprises a cold temperature equal to or less than said adsorption temperature. 
     
     
       22. The sorption cooling system of claim 19 wherein said hot source comprises a temperature of about 80° C. to about 350° C. and said cold source comprises a temperature of about -10° C. to about 50° C. 
     
     
       23. The sorption cooling system of claim 19 wherein said single rotary valve comprises three valve sections: a first valve section, a second valve section, and a third valve section wherein the first valve section simultaneously distributes the hot heat transfer fluid and the cold heat transfer fluid; the second valve section simultaneously and separately distributes desorbed refrigerant vapor to said condenser from said first sorption zone; and the third valve section simultaneously and separately distributes said vaporized refrigerant to said other sorption zone. 
     
     
       24. The sorption cooling system of claim 19 wherein the single rotary distribution valve comprises a low thermal conductivity material. 
     
     
       25. The sorption cooling system of claim 24 wherein the low thermal conductivity material is selected from the group consisting of plastic, ceramic, laminated fiber, rubber, wood, stainless steel, glass, and combinations thereof. 
     
     
       26. The sorption cooling system of claim 19 wherein said system comprises from 3 to 20 sorption zones. 
     
     
       27. The sorption cooling system of claim 19 wherein said sorption zone comprises a shell and tube exchanger having a shell side passage and a tube side passage said tube side passage comprising tubes having an inside coating containing the solid adsorbent and the heat transfer fluid passage being within said shell side passage. 
     
     
       28. The sorption cooling system of claim 19 wherein said sorption zone comprises a shell and tube heat exchanger having a shell side passage and a tube side passage, said tube side passage comprising tubes having an outside surface including an outside coating of the solid adsorbent on the outside surface and the heat transfer fluid passage being within said tube side passage. 
     
     
       29. The sorption cooling system of claim 28 wherein said tubes comprise an extended tube surface. 
     
     
       30. The sorption cooling system of claim 29 wherein said extended surface comprises longitudinal or helical fins. 
     
     
       31. The sorption cooling system of claim 30 wherein said extended surface comprises an adsorbent inventory-to-tube length ratio of from about 0.1 to about 5 Kg/m. 
     
     
       32. The sorption cooling system of claim 19 wherein the heat transfer fluid comprises water or paraffin.